But the Act, which dates from 1948, doesn't specify what constitutes "medical practice".

However, in 2001, in an attempt to regulate the country's growing permanent makeup industry, Japan's Ministry of Health, Labour and Welfare issued a statement in which it described "putting pigment on a needle tip and inserting it into the skin" as a medical practice that requires a medical practitioner's licence.

The raid on Taiki's studio was part of a broader crackdown on tattoo artists in which several were charged. The others paid their fines but Taiki refused.

In a country where tattoos are widely disliked for their perceived association with Yakuza gangsters, Taiki considers them an art form with a rich history.

He faced a choice: settle the fine and never tattoo in Japan again, or challenge a law that criminalises his work.

He decided to go to court in a landmark case that could determine the future of tattooing in the country.

FILMMAKER'S VIEW: The tattoos that divide Japan

By Hyoe Yamamoto

[Screengrab/Al Jazeera]

Despite its rich history, tattooing is a deeply divisive issue in Japan.

Many Japanese have a strong dislike for tattoos and those with them are often forbidden from entering swimming pools, gyms and hot springs. But why?

When Taiki decided to fight for the legitimacy of tattooing, he was taking on the philosophical, cultural and sociological objections to his art form.

Hyoe Yamamoto, filmmaker

Is it because of the widely accepted teachings of Confucius, which emphasise respect for the body? Could it be a consequence of the historical association with organised crime or because they are considered to be an anti-authoritarian mark in a society where a sign of rebellion is frowned upon?

I believe it's a combination of all three.

When Taiki decided to fight for the legitimacy of tattooing, he was taking on the philosophical, cultural and sociological objections to his art form and demanding that Japanese society open up and accept change.

But his crusade is complicated by a generational divide with older tattoo artists who believe being underground is an inherent part of the tradition of Japanese tattooing and resist the idea that it should be recognised as a legitimate profession.

Taiki is a reluctant activist. Reserved, modest and quiet, he was an artist in the process of honing his craft when he suddenly found himself at the centre of a controversy that will determine his fate.

The enormity of the challenge he has undertaken seems to dawn on him as we begin filming. But as time passes, he grows into the role, learning how to present himself and make his case.

It has been more than three years since his studio was raided and Taiki's battle continues.

He's determined to take his case all the way to the Supreme Court. And as the country prepares for an influx of international tourists and athletes in advance of the 2020 Tokyo Olympics, it seems the debate over tolerance towards tattoos is only going to heat up.